Magnetic speedometer



Aprifl 9, 1929. .1. K. OLSEN MAGNETIC SPEEDOMETER Filed NOV. 19, 1926 2 Sheets-Sheet Aprill 9, 1929. .1. K. OLSEN MAGNETIC SPEEDOMETER 2 Sheets-Sheet Filed NOV. 19, 1926 w a n Patented Apr. 3, 1929.

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JOHN K. OLSEN, OF CHICAGO, ILLINOIS, ASSIGNOR TO STEWART-WARNER SPEED- OIVIETER CORPORATION, OF CHICAGO, ILLINOIS, A CORPORATION OF VIRGINIA.

IVIAGNETEC SPEEDOMETER.

Application filed November 19, 1926. Serial No. 149,318.

The purpose of this invention is to provide an improved and simplified construction of a magnetic speedometer of the type employing a rotating annular magnet, the improvement being directed to economy of production and convenience of assembling and dis-assembling for repairs and replacements and other specific advantages in adjustment and operation. It consists in the elements and features of construction shown and described, as indicated in the claims.

In the drawings Figure 1 is a front or face view of the entire instrument.

Figure 2 is a section at the line, 2-2, on Figure 1.

Figure 3 is a sectional viewtaken on the line 33 of Figure 2.

Figure 4 is a detail axial section showing the drag element and the bearings of its spindle, said section being axial with respect to said parts.

Figure 5 is a sectional view of the parts shown in Figure 3 and taken as a section at line 55 on Figure 3.

Figure 6 is a detailed sectional view taken on the line 6-6 of Figure 2. V

Figure 7 is a detail section at line 7-7 on Figure5.

Figure 8 Fig. 3.

Figure 9 is a detail section at the line, 9-9, on Figure 4:.

Figure 10 is a detail section at the line, 1010, on Figure 8.

Figure 11 is a detail section at the line, 1111, on Figure 3. V

In the construction shown in the drawings 20 is the main die-cast frame member for supporting the operating parts of the speedometer. 21 is a sheet metal stamping constituting the casing of the entire instrument. 22 is a face plate. 23 is the glass covering same. 24 is the bezel ring securing the glass over the face plate. 25 is the speedometer rotor shaft, which constitutes also the in-leading driving shaft having its outer end portion bored and formed with in-struck crimps, 25, reducing the bore to square cross section at the zone of said crimps for afiording driving engagement with the squared end, 29 of the flexible shaft, 29, by which the instrument derives driving power from the vehicle which it serves. 26 is a counter-shaft through which is a section at the line, 8-8, on

rotation is communicated to the odometer train as hereinafter described. 26 and 25*, are intermeshing gears on the counter shaft and speedometer rotor shaft respectively. 15 is a cup member carried at the upper end of the shaft, 25, for mounting the split ring magnet, 28, said cup member being secured to the upper end of the rotor shaft, 25, by means of a nut, 25, clamping said cup member at a central aperture onto the end of the shaft against a flange, 25*", formed on the shaft. This cup member which is a sheet metal stamping is formed with an encompassing bead, 15, forming an inner groove, 15", for seating a spring ring, 29, which is adapted to be sprung into the groove, and is formed with the ends of the wire of which it is made flexed outwardly for extending through aperture, 15, which is formed in the wall of the mounting cup member, 15, in approximate radial alignment with the gap, 28 in the split ring magnet, 28, which is mounted seating upon the outside of the cup member, 15, stopped upon the shoulder formed by the bead, 15 31 is the field ring having an open center, 31*, and an arm, 31, extending inward radially as well as downwardly for forming a step bearing at 31, carrying a jewel, 32, for stepping the spindle, 33, of the drag member, 34. Said drag member is in the form of an inverted cup having an interrupted annular aperture, 34, in its horizontal web, 34,

through which aperture the radially depending arm, 31 of the field member, 31 extends for positioning the step bearing, 31, in the cup mounting member, 15. The drag member, 34:, has the margins of its annular aperture, 34, flanged upwardly, as seen at 34. for stiffening the horizontal web of said drag member, said member being in the form of an inverted cup having its flanged wall, 34 depending encompassing the magnet 28. Said drag member is secured at its center to the spindle, 33, by fittings, 35 and 36, screwed together, the fitting, 35, being drive fitted on the spindle. The upper end of the spindle is provided with a bearing 37, at the center of a spider top member, 37 which has four radial arms, 38, secured at the upper end of posts, 39, extending up from the die cast frame structure, and affords support for the field ring, 31, immediately above which and in contact with which theradial arms, 38, of said spider extend, affording opportunity for securement of the ring to said arms in any convenient manner, as by solderii'rg or by screws (not shown). 40 is the customary helical biasing spring secured at its outer end to the spider, 3?, and at its inn-er end to the spindle, 33, the means for securing its outer end being an Lip-struck linger, 3'2", from the spider, 37, which finger has lat-a1: ity of parallel slits, 37 between which the metal is struck out alternately in opposite directions forming oppositely facing very shallow loops, seen at 37 tlrrough wlrich the outer end part of the spring, to, is laced, as seen in Figures 5 and '2", the sfnririg and said loops being relatively dimensioi' ed so that the spring is held securely at said lacing, but is susceptible of being drawn longitudially in either direction to modify the length remaining inward from the part laced in the loops; and such adjustment constitutes a means for adjusting the tension of the spring for biasing the drag element against the drag of the magnet.

A desirable and important feature of this invention consists in the designing of the driving train from the ii -leading shaft which, as noticed, is also the speedometer r0 tor shaft, and correspondingly designing the frame structure in such form and arrangement that the gears may be formed integrally with or otherwise fixedly and permanently mounted on the respective shafts, and the shafts thus carrying the gears may be introduced longitudinally into the bearings cored and bored for them in the cast frame member, 20. Said bearings may be open from end to end, the several shafts b'eii'ig retained against longitudinal disp'lace'i'nent by keys inserted crosswise of said shafts respectively.

The rotor shaft, 25, inserted from the top and retained by a stop collar, 25, at the lower end, but is more accurately and definitely positioned by a forked key 25, set in from the backside striding the rotor shaft and seated in slots formed in the casting for receiving and accurately positioning it behind the flange, 25, against which the rotor magnet mounting cup, 15, is clamped, as described.

The counter shaft, 26', having its gear, 26?, as mentioned cut in the shaft meshing with the gear, 25, cut in the rotor and driving shaft, 25, has a second gear, 26, of slightly less diameter cut in the shaft at the end remote from the gear, 26 for meshing with a gear, a cut in the shaft, 41, and said shaft, 41, has at the end remote from the gear, 41, a worm gear, 41 for meshing withthe initial gear, 42 of the odometer mechanism on the odometer shaft, 42, as seen in dotted line in Figure 4. The bearings and housing for the shafts, 26, and 42, being eXtended through the casting from end to end, as seen inFigures 8 and 9, and the several and bearing enlargements on said shafts being dimensioned so that the shafts with their gears and In Figures 8 and 10 may be seen the key, 50,

inserted in the slot formed at in the cast mounting member, 20, engaging an annular groove, 26, in the" enlar ement, 26 which constitlltes the journal portion of the shaft, 26. in Figures 5) and 1 1 ni'ay' be seen the forked key, 51, infer-ted through the slot, 20 in the casting, 2t), and en gaging the" annular growl-1,41% in the 0 rnal, -21 e; v .e shaft, 41.

at of bearings and con- By this arran 'eme struction of shafts an gears, the nun'iber of parts in the entire mechanisn'i is greatly reduced and the construction rendered economical, and particularly the assembling is ef-' fee-ted with absolute certainty of correctness of pea tion and impossibility of error, rendering the assembling process rapid and economical. 7

It will be understood that the field ring, 31, is of magnetic metal, as soft iron, and that the magnet-supporting cup is of nonmagnetic metal, and that the part of the split ring, 29, which is flexed radially outward'in the aperture, 15, of the magnet-supporting cup and which stands lapping more or less of the magnetgap, is of magnetic metal and constitutes a shunt for the magnetic flux, for the wellunderstood purpose of facilitating calibration of the speedometer by adjusting the ring eircumferentially in the groove, 15, of the cup to vary the extent of the lap of the shunt over the magnet gap; and that the resiliency of the ring, which is contracted radially in being forced into the cup and reacts outwardly in entering the grooves, causes it to be snugly seated and held frictionally in the groove without liability to displacement durmg service.

I claim I 1. In a magnetic speedometer, in combination with a frame structure and a magnet rotor shaft journaled therein, a cup-shaped magnet carrying-rotor secured to the shaft; a' split ring magnet carried by the cup mounted thereon outside the marginal portion thereof, the cup having an encompassing out-struck bead forming exterior-1y a shoulder for stopping the magnet, and interiorly an annular recess for accommodating a ring, and a spring wire ring sprung into said recess, the cup having an aperture in the zone of the bead and recess positioned opposite the magnet gap and of greater angular extent than said gap, the ring having out-bent ends of the wire of which it is formed, extending through said aperture for adjustably lapping more or less of the magnet gap.

2. In a magnetic speedometer, in combination with a split ring magnet and a shaft on which it is mounted for rotation, a cupshaped stamping for mounting it on the shaft, having an encompassing bead struck outwardly from the cup flange onwhich the magnet is mounted, forming exteriorly a shoulder for stopping the magnet and interiorly a groove for accommodating a ring, an open spring Wire ring sprung into said groove, the cup flange having an aperture at the zone of the bead and groove positioned opposite the magnet gap, the ends of the wire forming the spring ring being outbent through said aperture for lapping the magnet poles at the magnet gap.

3. In the construction defined in claim 2, the aperture exceeding the annular extent of the dimension required for accommodating the spring wire ends which extend therethrough; whereby the spring ring may be adjusted about the axis of the magnet to lap its ends variably on the magnet poles and gap. I

4:. In the construction defined in claim 2, the magnet being mounted on the cup so as to be adjustable thereabout so as to vary the lap of the spring ring ends on the magnet poles and gap. I

5. In a magnetic speedometer, in combination with a'ring magnet and its rotor shaft, a mount for carrying the magnet on the shaft, consisting of a cup shaped member on Whose cylindrical wall or flange the magnet is carried, and by which it is spaced axially from the end of the shaft; a field ring diameter-ed for facing the magnet ring laterally thereof and having extending from its inner circum- Jierence an arm deflected laterally with respect to the plane of the field ring terminating in alignment with the shaftand provided with a step bearing for the drag element spindle, the drag element being an inverted cup having an interrupted annular aperture in its web for accommodating said step bearing arm of the field ring, said aperture being Wide enough to admit the step bearing terminal of said arm for assembling the drag element with the field ring and stepping the field ring in said bearing.

In testimony whereof, I have hereunto set my hand at Chicago, Illinois, this day of November, 1926.

JOHN K. OLSEN. 

